Add some linting rules for the CI (#587)

* enable one-var rule

* enable indent rule

* enable no-multiple-empty-lines rule

* enable no-empty rule

* enable no-trailing-spaces rule

* enable no-extra-semi rule

* add eslint rules to fix block spacing

* enable max-statements-per-line rule

* enable brace-style rule

* fix some spacing issues and add future rules

* add code suggestions

src/components/shell.js

@@ -8,7 +8,7 @@ define([], function () {
             } else {
                 window.open(url, target || '_blank');
             }
-            
+
         },
         canExec: false,
         exec: function (options) {